Association between traffic-related air pollution and anxiety hospitalizations in a coastal Chinese city: are there potentially susceptible groups?

Motor vehicle exhaust emissions have become the main source of urban air pollution in China, but few studies have explored the association of short-term exposure to traffic-related air pollutants (TRAPs) with anxiety disorders. Thus, we used an overdispersed, generalized additive model (GAM) to investigate the association between TRAPs and hospital admissions (HAs) for anxiety in Qingdao, a coastal Chinese city with high vehicle ownership. In addition, stratified analyses were performed by gender, age, season and hospitalization frequency (first admission and readmission). A positive association between TRAPs and HAs for anxiety was observed. Both inhalable particulate matter (PM 10) and nitrogen dioxide (NO 2) showed significant effects at lag 3 in the single-day lag structure, and each 10 μg/m3 increase in the concentrations was significantly associated with increases of 0.88% [95% confidence interval (CI): 0.04%, 1.72%] for PM 10 and 2.74% (0.45%, 5.08%) for NO 2 on anxiety hospitalizations. For fine particulate matter (PM 2.5) and carbon monoxide (CO), the strongest effects were found at lag05 and lag04 [2.67% (0.77%, 4.62%) and 0.19% (0.04%, 0.34%), respectively] in the multiday lag structure. The estimates of PM 2.5 were relatively robust after adjusting for other pollutants in the two-pollutant model. Stratified analyses indicated that the associations were stronger in females and younger individuals (<45 in age) than in males and elderly individuals (≥45 in age). Furthermore, the effects of PM 2.5 and CO were most obvious during the cold season. Regarding hospitalization frequency, only PM 2.5 was found to have a significant effect in the first-admission group. The results showed that short-term exposure to TRAPs, especially to PM 2.5 , was significantly associated with the increased risk of daily HAs for anxiety, which can help clinicians and policymakers better understand the effects of TRAPs to implement targeted interventions. • Short-term traffic-related air pollution was associated with anxiety hospitalizations. • The PM2.5-anxiety effects remained the most robust after adjusting for co-pollutants. • Females and younger individuals (<45 in age) were more vulnerable. • The effects of PM2.5 were significant during the cold season and in the first-admission group. [ABSTRACT FROM AUTHOR]